Electro-magnetic coupled piezolectric powering of electric vehicles

ABSTRACT

A device is disclosed, which includes: a charge portion with a plurality of piezoelectric elements embedded in a tire configured for a vehicle, a capacitor mechanically coupled to the tire and electrically coupled to the plurality of piezoelectric elements; a transmitter coil, mechanically coupled to the tire and electrically coupled to the capacitor through a discharge portion; wherein in response to an external radial pressure on the tire resulting from movement of the vehicle which causes a pressure on the plurality of piezoelectric elements, the plurality of piezoelectric elements produce an electrical charge on the capacitor, and wherein the discharge portion electrically connects the electrical charge on the capacitor to the transmitter coil to send electromagnetic power to the vehicle.

This application is a continuation of pending U.S. Pat. ApplicationSerial No. 17,366,157, filed Jul. 2, 2021, and entitled“ELECTRO-MAGNETIC COUPLED PIEZOLECTRIC POWERING OF ELECTRIC VEHICLES,”which is a continuation of U.S. Pat. Application Serial No. 16/993,527,filed Aug. 14, 2020, now U.S. Pat. No. 11,117,427, issued Sep. 14, 2021,and entitled “ELECTRO-MAGNETIC COUPLED PIEZOLECTRIC POWERING OF ELECTRICVEHICLES,” which claims the benefit of priority from U.S. ProvisionalPat. Application Serial No. 62/886,994 filed Aug. 15, 2019, entitled“SYSTEM AND METHOD OF ELECTROMAGNETIC COUPLED PIEZOLECTRIC CHARGING OFVEHICLE BATTERIES”, which are incorporated by reference herein in theirentirety.

BACKGROUND

Electric vehicles (EVs) can be classified as Hybrid (HEV), Plug-inhybrid (PHEV), Battery electric vehicles (BEV) and Fuel Cell ElectricVehicle (FCEV). HEVs combine an internal combustion engine (ICE) with anelectric motor and their batteries are charged using regenerativebraking technology which converts kinetic energy to electrical energy.PHEVs are similar to HEVs but their batteries can also be charged usingpower from an electrical outlet. BEVs do not have a gasoline engine,they are equipped with an electric motor that is operated using thepower stored in on-board batteries and are recharged from an electricaloutlet. FCEVs also have an electric motor which is powered byelectricity generated by combining the hydrogen stored in the on-boardtank with the oxygen in the air.

Although BEVs and FCEVs have zero tail-pipe emissions, they docontribute to global emissions. These emissions levels are dependent onthe energy sources used to produce the electricity used to charge theBEVs or to produce the hydrogen fuel for the FCEVs. The limited range ofEVs (in electric mode) has been a disadvantage that has curtailed thewidespread adoption of these vehicles.

Another obstacle negatively impacting the rate of adoption of EVs hasbeen the charging times. Level 1 (home charging) uses a 120 V 15 Ampelectrical outlet and can add a 40 mile range with an eight-hourovernight charge. Level 2 (home and public charging) is based on a 240 V30 Amp circuit which can add up to 180 miles with an eight-hourovernight charge. DC Fast Charging (public charging) is the fastestrecharging method currently available and can typically add 50 to 90miles in 30 minutes.

Public charging stations require substantial infrastructure developmentto make their use a viable option. It is clear that the above chargingsolutions will increase the load on the national electric grid, whichmight necessitate additional infrastructure, both in electricityproduction as well as distribution network, particularly during peak usehours.

Battery costs are another area of concern for EV adoption. Most EVscurrently are outfitted with Lithium Ion (Li-ion) batteries. Althoughthere have been dramatic reductions in the cost ($/Kwh) of Li-ionbatteries over the past decade, Li-ion batteries still represents a fairshare of the total cost of the EV. Furthermore, the mining andproduction practices of Cobalt, which is an indispensable material inthe production of Li-ion batteries, have come under increasing scrutinyby the international community over the past few years.

SUMMARY

A device is disclosed, which includes: a charge portion with a pluralityof piezoelectric elements embedded in a tire configured for a vehicle, acapacitor mechanically coupled to the tire and electrically coupled tothe plurality of piezoelectric elements; a transmitter coil,mechanically coupled to the tire and electrically coupled to thecapacitor through a discharge portion; wherein in response to anexternal radial pressure on the tire resulting from movement of thevehicle which causes a pressure on the plurality of piezoelectricelements, the plurality of piezoelectric elements produce an electricalcharge on the capacitor, and wherein the discharge portion electricallyconnects the electrical charge on the capacitor to the transmitter coilto send electromagnetic power to the vehicle.

A method is disclosed which includes: providing alternating chargeportions and discharge portions around a circumference of a tireconfigured for a vehicle; electrically charging a capacitive storagelayer in the tire with piezoelectric elements in the charge portionswhen each charge portion is under compression as the tire rotatescausing a pressure on the piezoelectric elements; and discharging thecapacitive storage layer to a transmitter coil with the dischargeportions to transmit power to a receiver coil on the vehicle, whereinthe transmitter coil is mechanically coupled to the tire andelectrically coupled to the capacitor through the discharge portion.

A system for electromagnetic coupled powering of an electric vehicle isdisclosed which includes: a plurality of charge portions and dischargeportions embedded in and sequentially arranged around a circumference ofa tire configured for a vehicle, wherein the plurality of chargeportions include a plurality of element modules each with at least onepiezoelectric element, a rectifier and a resistor; a capacitor embeddedin the tire and electrically coupled to the plurality of piezoelectricelements, wherein the piezoelectric elements are configured to generate,in response to time variance over time of a compressive force on thepiezoelectric element, a corresponding time-varying voltage differencebetween a top surface of the piezoelectric element and a bottom surfaceof the piezoelectric element, which induces a corresponding chargingcurrent to the capacitor; a transmitter coil embedded in the tire andelectrically coupled to the capacitor through a discharge portion,wherein the discharge portion acts as pressure switch to discharge thecapacitor in a time varying capacitor discharge current voltage throughthe transmitter coil, and the transmitter coil is configured toestablish, in response to the time varying discharge current through thecoil, a time varying magnetic field around the transmitter coil; whereinin response to an external radial pressure on the tire resulting frommovement of the vehicle which causes a pressure on the plurality ofpiezoelectric elements, the plurality of piezoelectric elements producean electrical charge on the capacitor, wherein the capacitor is acapacitor storage layer which includes a first plate and a second platethat is spaced from the first plate, the transmitter coil includes aconductor, the conductor having a conductor first end, a conductorsecond end, and a portion forming a loop, the loop having a firstwinding axis, the winding axis being colinear with a center axis of thetire, the conductor first end is electrically coupled to the first plateand the conductor second end is coupled to the second plate, and whereinthe discharge portion electrically connects the electrical charge on thecapacitor to the transmitter coil to send electromagnetic power to areceive coil on the vehicle, wherein the receiver coil is supported onthe vehicle by a receiver coil support that is configured to align thereceiver coil with the transmitter coil, and the receiver coil supportis further configured to position the receiver coil relative to thetransmitter coil such that, in response to the time varying magneticfield around the transmitter coil a time varying receiver coil currentis induced through the receiver coil.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures depict one or more implementations in accord with thepresent teachings, by way of example only, not by way of limitation. Inthe figures, like reference numerals refer to the same or similarelements.

FIG. 1 is the depiction of the piezoelectric material geometry in astatic neutral state as well as while generating a voltage undercompression and while deforming when exposed to an electric potential.

FIG. 2A shows the axial and radial components of the magnetic field of acircular current loop at a point at a distance z away in the axialdirection and a distance p away in the radial direction.

FIG. 2B shows magnetic lines representing the magnetic field produced bya current through a conductor loop.

FIG. 3A is the plot of the magnet field and induced Emf as a function ofradial distance away from the center of a circular current loop.

FIG. 3B is the plot of the magnetic field as a function of the axialdistance away from the center of the circular current loop.

FIG. 4 shows a partial cross-section view of an example implementationof a tire mounted on a wheel for electromagnetic coupled powering andcharging of an electric vehicle.

FIG. 5 shows a side view of an example implementation of a tire mountedon a wheel for electromagnetic coupled powering and charging of anelectric vehicle.

FIG. 6 is an electrical block diagram of an implementation.

FIG. 7A depicts perspective view of charge portions of thecharge/discharge layer.

FIG. 7B illustrates an exploded view of two modules of a charge portion.

FIG. 7C shows an electrical diagram of a charge portions of thecharge/discharge layer.

FIG. 8 depicts an exploded view of a charge portion of thecharge/discharge layer.

FIG. 9 is a three-dimensional perspective view of a tire assembly whichshows the respective positions of the receiver and transmitter coils aswell as the charge/discharge layer, capacitive storage layer and busbars.

FIG. 10 is an illustration of the plan view of the tire which shows thedimensions for the transmitter and receiver coils.

FIG. 11 is a view of a vehicle with a system as described herein.

FIG. 12 is a flowchart of an implementation of a process forelectromagnetic coupled powering and charging of an electric vehicle.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples to provide a thorough understanding of therelevant teachings. However, it should be apparent that the presentsubject matter may be practiced without such details. In otherinstances, well-known methods, procedures, components, and/or circuitryare described at a relatively high-level, without detail, to avoidunnecessarily obscuring aspects of the disclosed subject matter.

Reference Signs List

-   SI units-   Internal combustion engine (ICE)-   Hybrid electric vehicle (HEV)-   Plug-in hybrid electric vehicle (PHEV)-   Battery electric vehicle / All electric vehicle (BEV)-   Fuel cell electric vehicle (FCEV)-   Zero emission vehicle (ZEV)-   System on Chip computer (SoC)-   Single board computer (SBC)-   Greenhouse gases (GHG)

Selected Electrical Measurement Definitions

Quantity Name/Units Definition frequency f hertz (Hz) ⅟s force F newton(N) kg·m/s² pressure p pascal (Pa) = N/m² kg/m·s² energy E work joule(J) = N·m kg·m²/s² power P watt (W) = J/s kg·m²/s³ electric charge Qcoulomb (C) = A·s A·s voltage V volt (V)= W/A kg·m²/A·s³ current Iampere (A) = Q/s A capacitance C farad (F) A²·S⁴/kg·m² resistance R ohm(Ω) kg·m²/A²·s³ flux density B tesla (T) V·s/m², kg/A·s²

Implementations provide a self-contained method for power production forelectric vehicles (EVs). This, self-charging system will enable theperpetual generation of electrical power to charge vehicle batterieswhile the vehicle is in motion. Without the need for external sources ofpower, the system can increase driving range, reduce the cost of EVs aswell as the operating costs, reduce greenhouse gas emissions,reduce/eliminate time and infrastructure required for charging, reducestrain on the electrical grid, reduce reliance on fossil fuels and usherin the advent of a true zero emission EV.

Implementations use the normal force of gravity exerted on the contactpatch of the tire to compress piezoelectric material which, in turn,converts that force into an electric voltage. The voltage generated is afunction of the geometry of the piezoelectric material and the forceapplied to it. The generated voltage can be used to charge a capacitorthrough a conductor. Once the capacitor is charged and the tire hastraversed far enough so that the piezoelectric material is no longerunder compression, a discharge portion will discharge the accumulatedvoltage of the capacitor through the conductor causing the piezoelectricmaterial to undergo a deformation while it absorbs (dissipates) thevoltage. The conductor consists of multiple conducting circular currentloops (transmitting coil). Once the capacitor discharges through thetransmitter coil it will generate a varying magnetic field since thecurrent in the transmitter coil varies exponentially with respect totime. This generated magnetic field can produce an induced Emf in asecond coil comprised of multiple conducting circular current loops(receiver coil) in close proximity of the transmitter coil. Thegenerated voltage (Emf) in the receiver coil can then be supplied to theElectric Vehicle through electrical conditioning circuitry. Thisconditioning circuitry is well known to persons familiar with the artand is outside the scope of this description. The conditioned poweroutput can be used for charging the batteries on-board the ElectricVehicle and/or directly operating the Electric Vehicle.

Implementations make it possible to reduce the size of an EV’s on-boardbattery. This will result in a net weight reduction of the EV andgenerate cost savings from the smaller batter size. Furthermore, theLi-ion battery can be replaced and/or deployed alongside other lessexpensive battery technologies such as (but not limited to) NickelCadmium (NiCd) and Nickel-Metal Hydride (NiMH). Implementations alsoeffectively increase the driving range of the EV since it will bepossible to recharge the battery while the EV is in motion.

Implementations may reduce or eliminate the time required to charge theEV as well as the expense of charging infrastructure, private or public,and the cost of electricity used to charge the EV. It will also reduceor eliminate any additional demand on the national electric grid anddistribution network. Perhaps most importantly, implementations canreduce greenhouse gas emissions (GHG) including CO2. Any excess powergenerated can be used to compensate for losses in the electricalconditioning circuitry and/or maintain battery temperature for peakperformance (heating or cooling). Other potential uses of the excesspower include (1) active carbon capture using CO2 capture technologiessuch adsorption, (2) distributed computing using multiple low cost, lowpowered System on Chip (SoC) , Single board computer (SBC) inconjunction with high speed wireless data networks.

The examples set forth below are for BEVs although they can be appliedto practically any type of wheeled EV, including but not limited to,HEVs, PHEVs, e-buses, light, medium and heavy commercial vehicles,eScooters , electric powered motorcycles, etc.

FIG. 1 is the depiction of a piezoelectric material geometry 100 invarious states according to the piezo effect. In a static neutral state110, the piezoelectric material has no electric or mechanical forceapplied. In a compressed state 112, the piezoelectric material has amechanical force applied to it, causing the piezoelectric material togenerate a voltage. When exposed to an electric potential, thepiezoelectric material enters a physically deformed state 114.

The Piezo effect is the ability of certain materials to generate anelectrical charge (polarization of the material) in response to amechanical force exerted on them. Additionally, these materials undergoa controlled deformation when exposed to an electric field known as theinverse piezo effect. The aforementioned forces include compression andtension among others. Lead zirconate titanate ceramics is one suchmaterial. The performance characteristics and classifications of thesematerials are described in MIL-STD-1376B (Navy Type piezoelectricmaterial). While any piezoelectric material can be used, materialsexhibiting a combination of higher mechanical quality factor and Young’sModulus, lower electrical resistance and dielectric losses aredesirable. Hard PZT, Navy type I and Navy type III, are suitablematerials which meet the requirements.

In the piezo effect, the electrical charge produced by the material isproportional to the applied force and the geometry of the piezoelectricmaterial. For a rod the voltage and displacement (change in dimensions)of the piezoelectric material is given by:

$StaticVolatge_{rod} = g_{33} \times F_{3} \times \frac{height}{Area}\text{where g}_{33}\text{= Voltage constant}$

StaticDisplacement_(rod) = Δheight = d₃₃Vwhere d₃₃ = Charge constant

Research in the development of lead free piezoelectric materials hasbeen on going for more than a decade. NBT, sodium bismuth titanate; KNN,potassium sodium niobate; BF, bismuth ferrite; and BT barium titanateare new classes of materials that are result of the research. Thesenewly developed materials have yet to displace lead zirconate titanate’s(PZT) market dominance. The piezoelectric material response tocompression and subsequent decompression can be closely approximated bya triangular wave form with a positive and negative portion which can berectified using a full wave rectifier circuit to generate a DC voltage.It can be shown that the average voltage of triangular wave form isequal to ½ of the peak voltage.

FIG. 2A shows the axial and radial components of the magnetic field of acircular current loop at a point at a distance z away in the axialdirection and a distance p away in the radial direction. FIG. 2B showsmagnetic lines representing the magnetic field produced by a currentthrough a conductor loop.

Electric currents and magnetic fields. Biot-Savart Law and the moregeneralized Ampere’s Law relate magnetic fields to the currents as theirsources. The magnetic field in space around an electric current isproportional to the electric current which serves as its source, just asthe electric field in space is proportional to the charge which servesas its source. Ampere’s Law states that for any closed loop path, thesum of the length elements times the magnetic field in the direction ofthe length element is equal to the permeability times the electriccurrent enclosed in the loop.

FIG. 3A is the plot of the magnet field and induced Emf (example 1 EV-A)as a function of radial distance away from the center of a circularcurrent loop. The plot reveals that magnetic field reaches its maximumvalue as the distance from the center increases and a sharp decline asthe radial distance gets larger than the radius of the circular currentloop.

Magnetic field of a circular current loop The Axial (Bz) and Radial (Bp)components of the magnetic field at any point in space, outside theconductor, generated by a circular current loop can be calculated usingthe generalized formula:

$B_{p} = \frac{\mu_{0}I}{2\pi}\frac{z}{p\sqrt{\left( {\left( {a + p} \right)^{2} + z^{2}} \right)}}\left\lbrack {- K(k) + \frac{a^{2} + p^{2} + z^{2}}{\left( {a - p} \right)^{2} + z^{2}}E(k)} \right\rbrack$

$B_{z} = \frac{\mu_{0}I}{2\pi}\frac{1}{\sqrt{\left( {\left( {a + p} \right)^{2} + z^{2}} \right)}}\left\lbrack {K(k) + \frac{a^{2} - p^{2} - z^{2}}{\left( {a - p} \right)^{2} + z^{2}}E(k)} \right\rbrack$

$k^{2} = \frac{4ap}{\left( {a + p} \right)^{2} + z^{2}}$

where

-   a = loop radius-   z = axial distance-   p = radial distance-   I = current-   µ₀ = permeability of free space-   K, E = elliptic integrals of the first and second kind

The magnetic field on the axis of the circular current loop a distance zaway from the loop

$B_{z} = \frac{\mu_{0}Ia^{2}}{2\left( {a^{2} + z^{2}} \right)^{3/2}}$

It can be shown that the sum of the radial component is zero due to thesymmetry of the geometry of the circular current loop. The magnitude ofa magnetic field for a circular current loop at the center of the loopis given by:

$B_{0} = \frac{I\mu_{0}}{2a}\left( {atz = 0} \right)$

The magnetic field of multiple circular current loops are additivetherefore the magnetic field of N loops at the center of the loops isgiven by:

$B_{0} = N\frac{I\mu_{0}}{2a}\left( {atz = 0} \right)$

Emf due to changing magnetic field. Faraday’s Law of induction statesthat any change in the magnetic environment of a coil of wire will causea voltage (Emf) to be “induced” in the coil. No matter how the change isproduced, the voltage will be generated. The change could be produced bychanging the magnetic field strength, moving a magnet toward or awayfrom the coil, moving the coil into or out of the magnetic field,rotating the coil relative to the magnet field, etc. The induced Emf ina coil is equal to the negative of the rate of change of magnetic fluxtimes the number of turns in the coil and is directly proportional tothe time rate of change of magnetic flux through the coil.

$Emf = - N\frac{d\Phi_{B}}{dt}\text{where}\Phi_{B} = {\int{\overset{\rightarrow}{B} \cdot d\overset{\rightarrow}{A}}}$

$Emf = \varepsilon = - N\frac{d}{dt}BAcos\Theta$

where:

-   N = Number of Turns-   Φ_(B) = BA-   B = external Magnetic Field-   A = Area of coil-   ⊖ = the incident angle

Magnetic flux Φ is the product of the average normal component of themagnetic field and the area that it penetrates. Lenz’s Law states thatthe polarity of the induced Emf is such that it tends to produce acurrent that will create a magnetic flux to oppose the change inmagnetic flux through the coil. (FIGS. 2 a, 2 b ).

FIG. 3B is the plot of the magnetic field (example 1 EV-A) as a functionof the axial distance away from the center of the circular current loop.The plot shows the decreasing magnetic field as the axial distanceincreases.

Exponentially decaying magnetic field. The Emf generated due to anexponentially decaying magnetic field can be calculated as follows:

$Emf = - \frac{d\Phi_{B}}{dt} = - AB_{max}\frac{d}{dt}e^{- at} = aAB_{max}e^{- at}$

for a = 1/RC, where RC is the time constant, the Emf can be calculatedusing

$Emf = \frac{1}{RC}AB_{max}e^{\frac{- t}{RC}}$

Mutual inductance and coupling factor. The mutual inductance between twocoaxial filament current loops, one with radius r1 and another withradius r2, with the distance between centers x, can be calculated usingNeumann’s formula:

$M = \frac{\mu_{0}}{4\pi}{\iint\frac{\overset{\rightarrow}{ds}.{\overset{\rightarrow}{ds}}^{\prime}}{r}}$

which can be solved in the following form:

$M_{12} = - \mu_{0}\sqrt{r_{1}r_{2}}\left\lbrack {\left( {m - \frac{2}{m}} \right)K(m) + \frac{2}{m}E(m)} \right\rbrack$

$m = \frac{2\sqrt{r_{1}r_{2}}}{\sqrt{\left( {r_{1} + r_{2}} \right)^{2} + x^{2}}}$

where:

-   M = mutual inductance-   r1, r2 = radii of the two circular current loops-   x = the distance between the centers of the circular current loops-   K, E = elliptic integrals of the first and second kind

The coupling factor between two coils is defined by:

$k_{coupling} = \frac{M}{L1L2}$

Where:

-   M = Mutual inductance-   L1, L2 = self-inductance of the two coils-   Using the relations for self- and mutual-inductance, one can find    that 0 < k _(coupling) < 1.

The self-inductances L1 and L2 do not depend on the coil separation x,whereas the mutual inductance does.

Wheeler Approximation. Harold A. Wheeler developed formulas to giveapproximate inductances for various coil configurations. They areprimarily based on empirical measurements, and they are accurate to afew percent.

For a multi-layer air core coil

$L = \frac{0.8\left( {a^{2}xN^{2}} \right)}{6ax9bx10c}$

where:

-   a = average radius of windings-   b = length of the coil-   c = difference between the outer and inner radii of the coil.-   N = number of Turns-   L = inductance in µH-   all dimensions in inches. applies to coils with rectangular cross    section.

Current carrying capacity of a conductor. I.M. Onderdonk developed anequation while investigating conductor failure in high-voltage powertransmission lines due to arcing (short circuit). His equation relatescurrent, time and conductor size and assumes an adiabatic process. Theequation can be used to ascertain the time required for a giventemperature increase in the conductor due to joule heating.

$33\left( \frac{I}{A} \right)^{2}s = log_{10}\left( {\frac{\Delta T}{234 + T_{a}} + 1} \right)$

where:

-   I = current in amps-   A = cross-section area in circular mils-   s = the time in seconds the current is applied-   ΔT = the rise in temp from ambient or initial state-   Ta = the ref temp in deg C

FIG. 4 shows a partial cross-section view of an example implementationof a tire 410 mounted on a wheel 412 for electromagnetic coupledpowering and charging of an electric vehicle. The tire 410 includes atread ply layer 414 around the circumference of the tire for contactinga road surface. Below the tread ply layer 414 is a charge/dischargelayer 416. The charge/discharge layer 416 is divided into consecutivecharge portions and discharge portions around the circumference of thetire as described with reference to FIG. 5 below. Below thecharge/discharge layer 416 is a capacitive storage layer 418. Thecapacitive storage layer 418 may comprise one or more capacitors in oneor more layers as described further below. The tire 410 further mayinclude a number of embedded loop conductors or bus bars around thecircumference of the tire to electrically connect the other elements ofthe tire. In the illustrated implementation in FIG. 4 , the tire 410includes a positive bus bar 420, a common bus bar 422 and a dischargebus bar 424. The tire 410 further includes a transmitter coil 426 aroundthe circumference of the tire. In this implementation the transmittercoil 426 is located in a sidewall of the tire. The tire 410 may includeother basic vehicle tire structures such as a liner ply, carcass ply,belt ply, wheel bead, etc. that are not explicitly shown in FIG. 4 .

FIG. 5 shows a side view of the example implementation of the tire 410and wheel 412 for electromagnetic coupled charging of an electricvehicle introduced above. The charge/discharge layer 416 around thecircumference of the tire 410 is divided into consecutive chargeportions 510 and discharge portions 512. In the illustrated exampleimplementation, there are 10 charge portions 510 and 10 dischargeportions 512 alternating around the circumference of the tire 410. Thelength of the charge portions 510 and the discharge portions 512 areselected to be roughly equal to or relative to the length of the tirecontact patch area which depends on the specific tire dimensions. Thetire contact patch area is the area of the tire in contact with thesupporting surface at any one time characterized by a patch length and apatch width. The number of charge portions 510 and discharge portions512 may vary depending on the tire dimensions. The charge portion 510 iscomprised of an array (m x n) of modules as described further below. Thegenerated voltage from each charge portion is a function of the tirepatch area, force on the tire patch area, size of the conducive pressurepads which ultimately exert force on the piezoelectric modules, numberof array modules, number of piezoelectric elements per module as well astheir height and area of the elements. When each charge portion 510 isin contact with the supporting surface it generates a charge to thecapacitive storage layer 418 via the bus bars as described furtherbelow. As describe above each charge portion 510 is followed by adischarge portion 512. The discharge portion 512 discharges the electriccharge placed on the capacitive storage layer 418 by the precedingcharge portion 510. The discharge portion thus acts as a contact switchthat closes the circuit between the capacitive storage layer and thetransmitter coil 426 (FIG. 4 ) when the discharge portion comes undercompression. The discharge portion 512 is described further below withreference to FIG. 8 .

A capacitor is a passive two-terminal electrical device that is capableof storing energy in an electric field. A capacitor in its most basicform includes two conductors separated by an insulator generallyreferred to as a dielectric. A capacitor is characterized by acapacitance value (C) which is a function of the area of two parallelconductors and the separation distance between them (thickness of thedielectric material). The SI units for a capacitor is the Farad. Definedas the ratio of the positive or negative charge Q on each conductor tothe voltage V between them. The energy stored on a capacitor can becalculated using E_(cap) = ½ CV² where C is the capacitance and V is thevoltage. The energy stored on a capacitor can be discharged rapidlythrough a conductor. In a DC (Direct current) charging/dischargingcircuit the time constant is defined as τ = RC where R is the resistancein the circuit and C is the capacitance. Capacitors charge and dischargeexponential and it is generally accepted that they are fully (99%)charged or discharged within 5 time constants. The voltage of thecapacitor in an RC circuit is governed by:

$\begin{array}{l}{V_{cap} = V_{source}x\left( {1 - e^{- {t/{RC}}}} \right)\text{during charging,}} \\{\text{and}\mspace{6mu} V_{cap} = V_{source}xe^{- {t/{RC}}}\text{during discharge}\text{.}}\end{array}$

Plastic film capacitors can be broadly categorized into film/foil andmetallized film capacitors. The basic structure of a film/foil capacitorconsists of two metal foil electrodes and a plastic film dielectricbetween them. Metallized film capacitors are made of two metallizedfilms with plastic film as the dielectric. The plastic film is coatedwith a thin layer of zinc or aluminum. Some of the most commonly usedplastic film dielectrics include polyethylene naphthalate (PEN),polyethylene terephthalate (PET), and polypropylene (PP). Film/foilcapacitors offer high insulation resistance, high pulse handlingcapability, excellent current carrying capability, and good capacitancestability.

FIG. 6 is an electrical block diagram of an implementation forelectromagnetic coupled powering and charging of an electric car orvehicle. The electrical block diagram in FIG. 6 is divided into a tirecircuit 610, residing in the tire, and a vehicle circuit 612, residingon or in the vehicle. The tire circuit 610 includes a number of chargeportions 510 as described above. The charge portions shown in FIG. 6include charge portionA 510A, charge portionB 510B and charge portion510N, where N indicates a variable number of charge portions anddischarge portions can be used depending on the specific implementation.The charge portions 510A through 510N are collectively referred to ascharge portions 510. The charge portions 510 are each connected to thecapacitive storage layer 418. The connections of the charge portions 510to the capacitive storage layer are achieved by the positive bus bar andthe common bus bar (not shown in FIG. 6 ) as described further below.The capacitive storage layer 418 is connected to each of the dischargeportions 512A through 512N where again the discharge portions 512Athrough 512N are collectively referred to as discharge portions 512. Thecapacitive layer 418 is connected to the discharge portions 512 alsousing the positive bus bar and the common bus bar as described below.Thus both the charge portions 510 and the discharge portions 512 areconnected to the capacitor via the positive bus bar. Each of thedischarge portions 512 are connected to a transmitter coil 426 via adischarge bus bar and the common bus bar as described further below. Thetransmitter coil 426 produces an electromagnetic field to transmit powerto the receiver coil 614 on the vehicle for powering and charging thevehicle as described herein.

Again referring to FIG. 6 , the electrical block diagram furtherillustrates a vehicle circuit 612. The vehicle circuit 612 resides on orin the vehicle in a manner as shown in FIG. 11 . The vehicle circuitincludes a receiver coil 614. The receiver coil 614 preferably residesin close proximity of the transmitting coil as shown in FIGS. 10 and 11. The receiver coil 614 is placed on the vehicle located within theelectromagnetic field of the transmitter coil 426 to receive powergenerated from the tire circuit 610. The receiver coil 614 is connectedto a conditioning circuit 616 on the vehicle. The conditioning circuit616 inputs the electrical power of the receiver coil 614 and provides itto the vehicle including charging circuitry (not shown) for charging thevehicle’s batteries. The conditioning circuit 616 will vary depending onthe specific vehicle implementation.

The transmitter coil 426 is preferably comprised of multiple tightlywound conductors characterized by W_(Tx) windings and L_(Tx) layers andOD_(Tx) outer diameter and WG_(Tx) conductor wire gauge embedded in thesidewall of the tire, on the brake side, with one terminal connected tothe common bus bar 422 and the other to the discharge bus bar 424 (FIG.4 ).

The receiver coil 614 is preferably comprised of multiple tightly woundconductors characterized by W_(Rx) windings and L_(Rx) layers andOD_(Rx) outer diameter and WG_(Rx) conductor wire gauge. The receivercoil 614 in enclosed in a receiver coil housing for protecting thereceiver coil 614 from damage and preserving the geometrical stabilityof the coil. The receiver coil housing also provides anchor points forsecuring the receiver coil to the body, chassis or frame of the vehicleas described below. The receiver coil 614 presents two terminals to thepower conditioning circuitry on the vehicle. Preferably the area of thetransmitter coil 426 encompasses the area of the receiver coil 614.Also, the transmitter coil 426 and receiver coil 614 are preferablyconcentric, and have their respective circumscribed surfaces parallel toeach other with the centers separated by an axial distance z away fromeach other (as shown in FIG. 10 ), preferably as close as practicable,and for this relative geometry between the coils to be maintained duringoperation of the vehicle.

FIG. 7A depicts top perspective view of a charge portion 510 of thecharge/discharge layer 416 introduced above. The charge portion 510 maybe comprised of an array (m x n) of charge modules 710 enclosed in arubber housing 712. The array of modules in the example shown in FIG. 7are shown connected in series. Other combinations of series and parallelmodules could be used in the array. The charge portion 510 includes arectifier section 714 which rectifies the electrical output of thecharge modules 710. The rectifier section 714 preferably includes one ormore diodes 716 and may also include a resister as described below withreference to FIG. 7C. The rectifier section 714 includes a commonconnection 718 to the common bus bar 422 and a positive connection 720to the positive bus bar 420.

FIG. 7B illustrates an exploded view of two modules 710 of a chargeportion 510. In this example, the charge modules 710 each contain threepiezoelectric elements 722 encased in a module housing 724. Each chargemodule 710 has a top conductive pressure pad 728 and a bottom conductivepressure pad 726. The top conductive pressure pad 728 and the bottomconductive pressure pad 726 provide both a mechanical connection and anelectrical connection to the piezoelectric elements. In this example,the bottom conductive pressure pad 726 is connected to or integrallyformed with a top conductive pressure pad of an adjacent charge module.The module housing 724 is made of a lower durometer elastomer which willallow it to be compressed under pressure in order to permit compressionof the piezoelectric elements 722 by the top and bottom conductivepressure pads while the tire patch is under compression. In addition,the module housing 724 will also act as support for the conductivepressure pads. The charge modules 710 are embedded in the tire below thetire tread and are compressed when the tire patch containing the chargeportion containing the modules comes in contact with the pavement. Thegenerated voltage from each charge portion is a function of the tirepatch area, force on the tire patch area, size of the conductivepressure pads which ultimately exert force on the piezoelectric modules,number of array modules, number of piezoelectric elements per module aswell as their height. Multiple piezoelectric elements are used for forcedistribution as well as reduction of the number of points of failure.The modules may be connected in series to increase the generated voltagefor charging the capacitive storage layer. Each charge portion has twoconnections, one to the positive bus bar and one to the common bus bar.

FIG. 7C shows an electrical diagram of a charge portion 510 (FIG. 5 ) ofthe charge/discharge layer 416 (FIG. 4 ). As introduced above, eachcharge portion 510 includes a number of charge modules each containing anumber of piezoelectric elements. The piezoelectric elements of all thecharge modules for a charge portion 510 are combined and represented inFIG. 7C by piezoelectric element 730. Piezoelectric element 730 isconnected to the rectifier section 714 as described above with referenceto FIG. 7A. In this example, the rectifier section 714 includes fourdiodes 732 connected as a full wave rectifier 734. The positive terminal736 of the full wave rectifier is connected to the positive bus bar 420(FIG. 4 ) and the negative terminal 738 is connected to the common busbar 422 (FIG. 4 ). The charge portion 510 may include a resistor 740 inthe rectifier section 714 between the positive terminal 736 and thepositive bus bar 420. The resistor 740 provides resistance for an RCtime constant for charging the capacitive storage layer 418.

The capacitive storage layer 414 in the illustrated implementationconsists of multiple film/foil/dielectric layers wound along the length(circumference) of the tire. The width of the film/foil/dielectriclayers is preferably smaller than the contact patch width. Thefilm/foil/dielectric layers and terminals are encapsulated in a rubberhousing in the layers of the tire. The capacitive storage layer 414 hastwo connections, one to the positive bus bar and one to the common busbar. The voltage rating of the capacitive storage layer is preferablyabout 50% or more higher than the peak voltage generated by the chargingportion during normal operation in order to be able to cope with suddenvoltage spikes that may occur due to uneven road surfaces.

FIG. 8 depicts an exploded view of a discharge portion 512 of thecharge/discharge layer 416. The discharge portion 512 in thecharge/discharge layer is embedded in the tire below the tire tread andis compressed when the tire patch comes in contact with the pavement.The discharge portion 512 acts as a switch that closes the circuit toconnect the capacitive storage layer 418 to the transmitter coil 426 asdescribed above with reference to FIG. 6 . In the illustrate example,the discharge portion 512 includes a top layer 810 and a bottom layer812. The bottom layer 812 of the discharge portion 512 includes twolower conductors 814, 816 that come in contact via one or more topconductors 818 in the top layer 810 when the discharge portion 512 comesunder compression. The discharge portion 512 may include one or morespacers to keep the lower conductors 814, 816 apart from the topconductors 818 when the discharge portion 512 is not under compression.In this example, the discharge portion includes center spacers 822 andconductor spacers 820 within the outline of the lower conductors 814,816. One conductor 814 is connected to the positive bus bar 420 viaconnector 824 and the other conductor 816 is connected to the dischargebus bar 424 (FIG. 4 ) via connector 826. The discharge portion 512 couldinclude other configurations of contacts to provide a pressure sensitiveswitch to connect the capacitive storage layer 418 to the transmittercoil 426. For example, the discharge portion could include lowercontacts with interleaved conductive fingers that are connected by thetop conductors when the discharge portion comes under compression.

FIG. 9 is a three-dimensional view of a tire assembly forelectromagnetic coupled powering and charging of an electric vehicle.FIG. 9 shows the respective positions of the transmitter coil 426 insidethe tire 410, and receiver coil 614 located inside a receiver coilhousing 910. The receiver coil housing 910 is attached to the vehiclewith one or more chassis attachment arms 912. FIG. 9 further illustratesthe positions of the charge/discharge layer 416, the positive bus bar420, the discharge bus bar 424 and the common bus bar 422 in a cut awayportion of the tire 410. The storage layer 418 (only partially visible)is below the charge/discharge layer 416.

FIG. 10 is an illustration of the plan view of the tire 410 on the wheel412 to illustrate the dimensions for the transmitter coil 426 and thereceiver coil 614. The transmitter coil 426 is located in the tire 410as described above. The receiver coil 614 is located in the receivercoil housing 910. The horizontal distance between the transmitter coil426 and the receiver coil 614 is represented by distance “z”. Thereceiver coil 614 is located a vertical distance “p” from the centeraxis of the wheel 412 and the transmitter coil 426 is located a verticaldistance “a” from the center axis of the wheel 412. The verticalseparation distance of the receiver coil 614 and the transmitter coil426 can be determined by subtracting distance “p” from distance “a”.

FIG. 11 is a view of a vehicle 1110 with a system for electromagneticcoupled charging of an electric vehicle as described herein. A tire 410includes the components described above including a transmitter coil(not shown). A receiver coil (not visible) is mounted inside thereceiver coil housing 910 that is mounted to the vehicle 110 withseveral chassis attachment arms 912. One of ordinary skill in the artwill recognize that other attachment arm configurations could be used tomount the receiver coil housing 910 to the vehicle 110.

FIG. 12 is a flowchart of an implementation of a process forelectromagnetic coupled powering and charging of an electric vehicle.The first step (1210) of an example implementation includes providingalternating charge portions and discharge portions around thecircumference of a tire configured for a vehicle. The charge portion mayinclude one or more element modules, each having at least onepiezoelectric element in an element module housing. The modules mayfurther include a lower conductive pressure pad on a top surface of theelement module housing, an upper conductive pressure pad on a bottomsurface of the element module housing, where the element module housingis a lower durometer material than the piezoelectric elements such thatcompression force applied to the tire causes the piezoelectric elementsto produce the electrical charge on the capacitor. The discharge portionacts as pressure switch to discharge the capacitor in a time varyingdischarge current through the transmitter coil, and the transmitter coilis configured to establish, in response to the time varying dischargecurrent through the coil, a time varying magnetic field around thetransmitter coil to transmit power to the receiver coil located on thevehicle.

The second step (1220) of the implementation of FIG. 12 includeselectrically charging a capacitive storage layer in the tire withpiezoelectric elements in the charge portions when each charge portionis under compression as the tire rotates. The capacitor storage layermay include one or more capacitors. The capacitors of the capacitivestorage layer may include a first plate and a second plate that isspaced from the first plate, the transmitter coil includes a conductor,the conductor having a conductor first end, a conductor second end, anda portion forming a loop, the loop having a first winding axis, thewinding axis being colinear with a center axis of the tire, theconductor first end is electrically coupled to the first plate and theconductor second end is coupled to the second plate.

The final step (1230) of the implementation of FIG. 12 includesdischarging the capacitive storage layer to a transmitter coil with thedischarge portions to transmit power to a receiver coil on the vehicle.The process may further include a receiver coil being supported by thevehicle; wherein the receiver coil has a second winding axis, thereceiver coil is supported on the vehicle by a receiver coil supportthat is configured to align the second winding axis colinear with thefirst winding axis, and the receiver coil support is further configuredto position the receiver coil relative to the transmitter coil suchthat, in response to the time varying magnetic field around thetransmitter coil a time varying receiver coil current is induced throughthe receiver coil. The process may further include the receiver coilconnected to a conditioning circuit on the vehicle to supply power tothe vehicle using the time varying receiver coil current and wherein thetransmitting coil is embedded in the sidewall structure of the tire suchthat upon the tire being mounted to a wheel to form a wheel-tirecombination, and the wheel-tire combination is mounted to the vehicle,and the winding axis is colinear with an axis of rotation of thewheel-tire combination.

Example 1 - Electric Vehicle A (EV-A). In this first example, the curbweight of the vehicle is 1,085 kg. The weight of the vehicle exerts aforce of approximately 2,927 N force on the tire patch area of each ofthe two rear wheels with a 45/55 front rear weight distribution. The OEMtires specified for the rear wheels of a vehicle in this class areP185/60R15 84T tires with a no-load outside diameter of 603 mm. Thecircumference of the tire is 1.89 m which at velocity of 2.78 m/s(roughly 10 km/h) will have gone through a full revolution in onesecond. EV-A has an average power requirement of 255 W/mi (158 W/km). At40 km/h the average power requirement is approximately 6.3 kW.

In Example 1, the contact patch length of tire is 97 mm (length) whichtranslates into 9 charge/discharge portions along the circumference ofthe tire. The voltage generation (charge portion) consists of any arrayof 12 modules, arranged in a 3 × 4 configuration, with each 15 mmdiameter module housing having three (3) Navy type I piezoelectricelements, arranged in a concentric ring one half of the diameter of themodule. The elements are preferably positioned angularly equidistantwith a 2.7 mm outer diameter and 3 mm in height. The elements areinterconnected in series with conducting electrical connections such asthe conductive pressure pads described above. The charge portion isconnected to the common and positive bus bars through a full waverectifier and a 2 ohm resistor (R1). The storage layer, or capacitivestorage layer, consists of a 220 microfarad capacitor rated at 2,000Volts connected to the common and positive bus bars. The dischargepotion consists of two conductors that make contact when the dischargeportion comes under compression and complete the circuit between thepositive and discharge bus bars. The transmitter coil (circular currentloops of conducting magnet/enamel wire) consists of 2 windings by 3layers 4 AWG enamel wire with outer diameter of 520 mm embedded in thesidewall of the tire. The length of the transmitter coil is 9.8 metersand the weight is 1.84 kg. The transmitter coil is connected to thedischarge and common bus bars which allows the capacitive storage layerto discharge through the transmitter coil (in series with a 2 ohm bleedresistor (R2) ) every time a discharge potion comes under compression.

Again referring to Example 1, the receiver coil consists of a 6 windingby 6 layers 10 AWG enamel wire with and outer diameter of 460 mm. Thelength of the transmitter coil is 52 meters and the weight is 2.43 kg.The coupling factor between the transmitter and receiver coils is 0.44using the Wheeler approximation. The receiver coil must be positioned inclose proximity to the transmitter coil, in this case, 50 mm axialdistance with the circumscribed surfaces of the two coils parallel toeach other. The axial component of the magnetic field (Bz) can beevaluated at any point in space using the formulas described above.Bzmax calculated at the center of the receiver coil (FIG. 10 ) is 8.89E-03 Tesla which is an exponentially decaying field. This field willproduce mean power (P = I²R) of 717 Watts with a mean voltage of 24.76volts DC and mean current of 11.23 Amps across a 2.2 ohm constant load.The combined power production from both rear wheel assemblies isapproximately 1,434 Watts per rotation at speeds in excess of 10 kph.The power output will increase as a function of vehicle speed and tirerotations. As an example, with the current configuration, at 40 km/h (~25 mph) the total power output is 7.2 kW and at 90 km/h (~ 56 mph) thepower output is approximately 18.6 kW.

Example 2 - Electric Vehicle B (EV-B). The curb weight of the vehicle is1,343 kg. The weight of the vehicle exerts a force of approximately3,294 N force on the tire patch area of each of the two rear wheels witha 50/50 front rear weight distribution. The OEM tires specified for therear wheels are P155/70R19 84Q tires with a no-load outside diameter of696 mm. The circumference of the tire is 2.18 m which at velocity of2.78 m/s (roughly 10 km/h) will have gone through a full revolution inone second. EV-B has an average power requirement of 260 Wh/mi (161Wh/km). At 40 km/h the average power requirement is approximately 6.5kW. The contact patch length of tire is 136 mm (length) which translatesinto 8 charge/discharge portions along the circumference of the tire.The voltage generation (charge portion) consists of any array of 12modules, arranged in a 3 × 4 configuration, with each 15 mm diametermodule housing three (3) Navy type I piezoelectric elements, arranged ina concentric ring one half of the diameter of the module with elementspositioned angularly equidistant, elements 2.5 mm outer diameter and 3mm height interconnected in series with conducting electricalconnections such as the conductive pressure pads described above. Thecharge portion is connected to the common and positive bus bars througha full wave rectifier and a 2 ohm resistor (R1).

The capacitive storage layer consists of a 220 microfarad capacitorrated at 2,000 Volts and is also connected to the common and positivebus bars. The discharge potion consists of two conductors that makecontact when the discharge portion comes under compression and completethe circuit between the positive and discharge bus bars. The transmittercoil (circular current loops of conducting magnet/enamel wire) consistsof 2 windings by 3 layers 4 AWG enamel wire with outer diameter of 580mm embedded in the sidewall of the tire. The length of the transmittercoil is 11 meters and weight is 2.1 kg. The transmitter coil isconnected to the discharge and common bus bars which allows thecapacitive storage layer to discharge through the transmitter coil (inseries with a 2 ohm bleed resistor (R2)) every time a discharge potioncomes under compression. The receiver coil consists of a 6 winding by 6layers 10 AWG enamel wire with and outer diameter of 520 mm. The lengthof the transmitter coil is 58.8 meters and the weight is 2.75 kg. Thecoupling factor between the transmitter and receiver coils is 0.47 usingthe Wheeler approximation. The receiver coil must be positioned in closeproximity to the transmitter coil, in this case, 50 mm axial distancewith the circumscribed surfaces of the two coils parallel to each other.The axial component of the magnetic field (Bz) can be evaluated at anypoint in space using the formulas described above.

Bzmax calculated at the center of the receiver coil (FIG. 3 ) is 8.97E-03 Tesla which is an exponentially decaying field. This field willproduce mean power (P = I²R) of 925 Watts with a mean voltage of 31.94volts DC and mean current of 11.24 Amps across a 2.8 ohm constant load.The combined power production from both rear wheel assemblies isapproximately 1,850 Watts per rotation at speeds in excess of 10 kph.The power output will increase as a function of vehicle speed and tirerotations. As an example, with the current configuration, at 40 km/h (~25 mph) the total power output is 9 kW and at 90 km/h (~ 56 mph) thepower output is approximately 20 kW.

Example 3 - Electric Vehicle C (EV-C). The curb weight of the vehicle is2,208 kg. The weight of the vehicle exerts a force of approximately5,321 N force on the tire patch area of each of the two rear wheels witha 50/50 front rear weight distribution. The OEM tires specified for therear wheels are P235/65R18 106 V tires with a no-load outside diameterof 758 mm. The circumference of the tire is 2.38 m which at velocity of2.78 m/s (roughly 10 km/h) will have gone through a full revolution inone second. EV-C has an average power requirement of 360 Wh/mi (224Wh/km). At 40 km/h the average power requirement is approximately 9.3kW. The contact patch length of tire is 167 mm (length) which translatesinto 7 charge/discharge portions along the circumference of the tire.The voltage generation (charge portion) consists of any array of 12modules, arranged in a 3 × 4 configuration, with each 15 mm diametermodule housing three (3) Navy type I piezoelectric elements, arranged ina concentric ring one half of the diameter of the module with elementspositioned angularly equidistant, elements 2.3 mm outer diameter and 3mm height interconnected in series with conducting with conductingelectrical connections such as the conductive pressure pads describedabove. The charge portion is connected to the common and positive busbars through a full wave rectifier and a 2 ohm resistor (R1).

The capacitive storage layer consists of a 270 microfarad capacitorrated at 2,000 Volts and is also connected to the common and positivebus bars. The discharge potion consists of two conductors that makecontact when the discharge portion comes under compression and completethe circuit between the positive and discharge bus bars. The transmittercoil (circular current loops of conducting magnet/enamel wire) consistsof 2 windings by 3 layers 4 AWG enamel wire with outer diameter of 620mm embedded in the sidewall of the tire. The length of the transmittercoil is 11.7 meters and the weight is 2.2 kg.

The transmitter coil is connected to the discharge and common bus barswhich allows the capacitive storage layer to discharge through thetransmitter coil (in series with a 2 ohm bleed resistor (R2)) every timea discharge potion comes under compression. The receiver coil consistsof a 6 winding by 7 layers 10 AWG enamel wire with and outer diameter of560 mm. The length of the transmitter coil is 73.9 meters and the weightis 3.46 kg. The coupling factor between the transmitter and receivercoils is 0.49 using the Wheeler approximation. The receiver coil must bepositioned in close proximity of the transmitter coil, in this case, 50mm axial distance with the circumscribed surfaces of the two coilsparallel to each other. The axial component of the magnetic field (Bz)can be evaluated at any point in space using the formulas describedabove.

Bzmax calculated at the center of the receiver coil (FIG. 3 ) is 8.66E-03 Tesla which is an exponentially decaying field. This field willproduce mean power (P = I²R) of 984 Watts with a mean voltage of 33.95volts DC and mean current of 11.24 Amps across a 3.2 ohm constant load.The combined power production from both rear wheel assemblies isapproximately 1,969 Watts per rotation at speeds in excess of 10 kph.The power output will increase as a function of vehicle speed and tirerotations. As an example, with the current configuration, at 40 km/h (~25 mph) the total power output is 7.8 kW and at 90 km/h (~ 56 mph) thepower output is approximately 19.6 kW.

The coils in the above examples are simple circular tightly wound coilswith a square and/or rectangular cross section, while coils with othercross-sectional shapes may also be used. The receiver coil needs to beaffixed rigidly to the vehicle such that there is virtually nodisplacement since the axial distance and/or angular deviation canadversely affect the power output of receiver coil. The sidewalls of thetires need to be reinforced, similar to that of run-flat tires, in orderto reduce stresses on the transmitter coil, help maintain the coilgeometry, and also protect the transmitter coil against deformation incase of tire pressure loss.

It should be noted that tuning of the parameters such as (i) thereceiver coil configuration (layers and windings), (ii) receiver coilouter diameter, (iii) capacitor size (capacitance), (iv) adjustment ofseparation distance between the transmitter and receiver coils, (v)transmitter voltage generation and coil outer diameter, etc. can betailored to produce the desired power output.

While the foregoing has described what are considered to be the bestmode and/or other examples, it is understood that various modificationsmay be made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that the teachings may beapplied in numerous applications, only some of which have been describedherein.

Unless otherwise stated, all measurements, values, ratings, positions,magnitudes, sizes, and other specifications that are set forth in thisspecification, including in the summary points that follow, areapproximate, not exact. They are intended to have a reasonable rangethat is consistent with the functions to which they relate and with whatis customary in the art to which they pertain.

Language is intended and should be interpreted to be as broad as isconsistent with the ordinary meaning of the language is used in thecontext of this disclosure, and to encompass all structural andfunctional equivalents.

Except as stated immediately above, nothing that is stated orillustrated is intended or should be interpreted to cause dedication ofany component, step, feature, object, benefit, advantage, or equivalentto the public.

It will be understood that terms and expressions used herein have theordinary meaning accorded to such terms and expressions in theirrespective areas of inquiry and study except where specific meaningshave otherwise been set forth herein. Relational terms such as first andsecond and the like may be used solely to distinguish one entity oraction from another without necessarily requiring or implying any actualsuch relationship or order between such entities or actions. The terms“comprises,” “comprising,” and any other variation thereof, are intendedto cover a non-exclusive inclusion, such that a process, method,article, or apparatus that comprises a list of elements does not includeonly those elements but may include other elements not expressly listedor inherent to such process, method, article, or apparatus. An elementpreceded by “a” or “an” does not, without further constraints, precludethe existence of additional identical elements in the process, method,article, or apparatus that comprises the element.

In the foregoing Detailed Description, it can be seen that variousfeatures are grouped together in various examples for the purpose ofstreamlining the disclosure. This method of disclosure is not to beinterpreted as reflecting an intention that any summary point requiresmore features than it expressly recites.

What is claimed is:
 1. A device, comprising: a charge portion with atleast one piezoelectric element embedded in a tire configured for avehicle; a capacitor mechanically coupled to the tire and electricallycoupled to the charge portion; a transmitter coil, mechanically coupledto the tire and electrically coupled to the capacitor through adischarge portion; wherein in response to an external radial pressure onthe tire resulting from movement of the vehicle which causes a pressureon the at least one piezoelectric element of the charge portion, the atleast one piezoelectric element produces an electrical charge on thecapacitor, and wherein the discharge portion electrically connects theelectrical charge on the capacitor to the transmitter coil to sendelectromagnetic power from the tire to the vehicle.
 2. The deviceaccording to claim 1, wherein the electromagnetic power sent from thetire to the vehicle is used to charge a battery on the vehicle toprovide power to the vehicle and provide power to other vehicle systemsfor functions selected from a group consisting of maintaining a batterytemperature and powering a distributed computing system.
 3. The deviceaccording to claim 1, wherein the at least one piezoelectric element isconfigured to generate, in response to time variance over time of acompressive force on the at least one piezoelectric element, acorresponding time-varying voltage difference between a top surface ofthe at least one piezoelectric element and a bottom surface of the atleast one piezoelectric element, which induces a corresponding chargingcurrent to the capacitor.
 4. The device according to claim 1, furthercomprising a plurality of discharge portions and a plurality of chargeportions, wherein the plurality of charge portions and the plurality ofdischarge portions alternate consecutively around a circumference of thetire in a charge/discharge layer below a tread ply layer of the tire,wherein the plurality of charge portions include at least one elementmodule, a rectifier and a resistor.
 5. The device according to claim 4,wherein the at least one element module comprises: the at least onepiezoelectric element; an element module housing to mechanically supportthe at least one piezoelectric element; a bottom conductive pressure padon a bottom surface of the element module housing; a top conductivepressure pad on a top surface of the element module housing, and whereinthe element module housing is of a lower durometer material than thepiezoelectric elements such that compression force applied to the tirecauses the piezoelectric elements to produce the electrical charge onthe capacitor.
 6. The device according to claim 1 wherein the dischargeportion acts as pressure switch to discharge the capacitor in a timevarying discharge current through the transmitter coil, and thetransmitter coil is configured to establish, in response to the timevarying discharge current through the coil, a time varying magneticfield around the transmitter coil to transmit power to a receiver coillocated on the vehicle.
 7. The device according to claim 1, wherein thecapacitor is a capacitor storage layer extending around thecircumference of the tire which includes a first plate and a secondplate that is spaced from the first plate, the transmitter coil includesa conductor, the conductor having a conductor first end, a conductorsecond end, and a portion forming a loop in a sidewall around acircumference of the tire, the loop having a first winding axis, thewinding axis being colinear with a center axis of the tire, theconductor first end is electrically coupled to the first plate and theconductor second end is coupled to the second plate.
 8. The deviceaccording to claim 1, wherein the transmitter coil has a first windingaxis, and wherein the system further comprises a receiver coil beingsupported by the vehicle; wherein the receiver coil has a second windingaxis, the receiver coil is supported on the vehicle by a receiver coilsupport that is configured to align the second winding axis colinearwith the first winding axis, and the receiver coil support is furtherconfigured to position the receiver coil relative to the transmittercoil such that, in response to a time varying magnetic field around thetransmitter coil a time varying receiver coil current is induced throughthe receiver coil.
 9. The device according to claim 8, wherein thereceiver coil is connected to a conditioning circuit on the vehicle tosupply power to the vehicle using the time varying receiver coilcurrent.
 10. The device according to claim 4, wherein the transmittercoil is embedded in a sidewall structure of the tire such that upon thetire being mounted to a wheel to form a wheel-tire combination, and thewheel-tire combination is mounted to the vehicle; wherein: in responseto an external radial pressure on the tire resulting from movement ofthe vehicle which causes a pressure on the at least one piezoelectricelement, the at least one piezoelectric element produces an electricalcharge on the capacitor, wherein the capacitor is a capacitor storagelayer which includes a first plate and a second plate that is spacedfrom the first plate, the transmitter coil includes a conductor, theconductor having a conductor first end, a conductor second end, and aportion forming a loop in a sidewall around a circumference of the tire,the loop having a first winding axis, the winding axis being colinearwith a center axis of the tire, the conductor first end is electricallycoupled to the first plate and the conductor second end is coupled tothe second plate, the plurality of discharge portions electricallyconnect the electrical charge on the capacitor to the transmitter coilto send electromagnetic power to a receive coil on the vehicle, whereinthe electromagnetic power sent from the tire to the vehicle is furtherapplied to vehicle system functions selected from the group consistingof maintaining a battery temperature and powering a distributedcomputing system, and the receiver coil is supported on the vehicle by areceiver coil support that is configured to align the receiver coil withthe transmitter coil, and the receiver coil support is furtherconfigured to position the receiver coil relative to the transmittercoil such that, in response to the time varying magnetic field aroundthe transmitter coil a time varying receiver coil current is inducedthrough the receiver coil.
 11. A method comprising: electricallycharging a capacitive storage layer in a tire with at least onepiezoelectric element in a charge portion embedded in the tire when thecharge portion is under compression as the tire rotates causing apressure on the piezoelectric element; discharging the capacitivestorage layer to a transmitter coil to transmit power from the tire to areceiver coil on a vehicle; and providing the power transmitted from thetire to the vehicle to power vehicle systems.
 12. The method accordingto claim 11, further comprising providing the power transmitted from thetire to the vehicle to other vehicle systems for functions selected froma group consisting of maintaining a battery temperature and powering adistributed computing system.
 13. The method according to claim 11,wherein the at least one piezoelectric element is configured togenerate, in response to time variance over time of a compressive forceon the at least one piezoelectric element, a corresponding time-varyingvoltage difference between a top surface of the at least onepiezoelectric element and a bottom surface of the at least onepiezoelectric element, which induces a corresponding charging current tothe capacitive storage layer.
 14. The method according to claim 11,further comprising charging and discharging the capacitive storage layerwith a plurality of charge portions and a plurality of dischargeportions which alternate consecutively around a circumference of thetire in a charge/discharge layer below a tread ply layer of the tire.15. The method according to claim 14, wherein the plurality of chargeportions include at least one element module, a rectifier and aresistor, and the at least one element module comprises: the at leastone piezoelectric element; an element module housing to mechanicallysupport the at least one piezoelectric element; a lower conductivepressure pad on a top surface of the element module housing; an upperconductive pressure pad on a bottom surface of the element modulehousing, and wherein the element module housing is a lower durometermaterial than the piezoelectric elements such that compression forceapplied to the tire causes the piezoelectric elements to produce theelectrical charge on the capacitive storage layer.
 16. The methodaccording to claim 14 further comprising, discharging the capacitivestorage layer in a time varying discharge current through thetransmitter coil in response to pressure on the plurality of dischargeportions, and transmitting power to the receiver coil located on thevehicle with a time varying magnetic field around the transmitter coilin response to the time varying discharge current through the coil. 17.The method according to claim 11, further comprising extending thecapacitor storage layer around the circumference of the tire, whereinthe capacitive storage layer includes a first plate and a second platethat is spaced from the first plate.
 18. The method according to claim11, further comprising: providing a transmitter coil with a firstwinding axis; providing a receiver coil supported by the vehicle,wherein the receiver coil has a second winding axis; and aligning thesecond winding axis colinear with the first winding axis to position thereceiver coil relative to the transmitter coil such that, in response toa time varying magnetic field around the transmitter coil a time varyingreceiver coil current is induced through the receiver coil.
 19. Themethod according to claim 18, further comprising: connecting thereceiver coil to a conditioning circuit on the vehicle to supply powerto the vehicle using the time varying receiver coil current; andembedding the transmitting coil in a sidewall structure of the tire suchthat upon the tire being mounted to a wheel to form a wheel-tirecombination, and the wheel-tire combination being mounted to thevehicle, the winding axis becomes colinear with an axis of rotation ofthe wheel-tire combination.
 20. The method according to claim 11,further comprising: producing an electrical charge on the capacitivestorage layer in response to an external radial pressure on the tireresulting from movement of the vehicle which causes a pressure on the atleast one piezoelectric element; and wherein the capacitive storagelayer includes a first plate and a second plate that is spaced from thefirst plate, the transmitter coil includes a conductor, the conductorhaving a conductor first end, a conductor second end, and a portionforming a loop in a sidewall around a circumference of the tire, theloop having a first winding axis, the winding axis being colinear with acenter axis of the tire, the conductor first end is electrically coupledto the first plate and the conductor second end is coupled to the secondplate.